(RADIO FREE EUROPE) NEW YORK – The Iranian foreign minister has dismissed what he called Donald Trump’s “genocidal taunts” and warned the U.S. president not to threaten Iran.

Amid rising tensions between Washington and Tehran, Trump tweeted early on May 20, “If Iran wants to fight, that will be the official end of Iran.”

“Never threaten the United States again!” he wrote, hours after a rocket was fired into the heavily fortified Green Zone in the Iraqi capital, Baghdad, and landed about 500 meters from the U.S. Embassy.

There was no claim of responsibility for the rocket attack, which caused no casualties or significant damage.

The remarks came amid concerns about a potential military conflict between the United States and Iran.

Washington has ordered a beefing up of U.S. military assets in the Middle East and Persian Gulf, citing ” imminent threats” from Iran, and ordered the evacuation of personnel from the U.S. Embassy in neighboring Iraq

Tehran has dismissed the U.S. allegations, and accused Washington of an “unacceptable” escalation of tensions.

Both sides have said they do not want a war.

On May 20, British Foreign Secretary Jeremy Hunt said that Iran should not doubt the United States’ resolve, warning that “if American interests are attacked, they will retaliate.”

Hunt told journalists in Geneva that Britain wanted “the situation to deescalate,” and urged Iran “to pull back from the destabilizing activities it does throughout the region.”

Saudi Foreign Minister Adel al-Jubeir said on May 19 that Riyadh also did not want military conflict with Iran, but added, “if the other side chooses war, the kingdom will fight this with all the force and determination and it will defend itself, its citizens, and its interests.”

Saudi Arabia, a U.S. ally and Iran’s regional rival, has accused Tehran of ordering last week’s drone strikes on oil installations in the kingdom that was claimed by Yemen’s Shi’ite Huthi rebels.

Relations between Iran and the United States plummeted a year ago when Trump pulled out of the 2015 nuclear deal which curbed Iran’s nuclear program in exchange for relief from crippling sanctions.

Since then, Washington has stepped up its rhetoric and reimposed sanctions.

In announcing the U.S. pullout from the nuclear agreement, Trump said the terms were not tough enough to prevent Iran from developing nuclear weapons and did not address Iran’s missile program or Tehran’s support for militants in the region.

Iran denies it supports insurgent activity, including in Yemen, and has said its nuclear program is strictly for civilian energy purposes.